Chop your courgettes, leeks and carrots into small pieces.
In a tall pan, heat a little olive oil and 2 tablespoons of butter and add the shopped vegetables so they can gently soften and caramelise. This should take around 10 minutes.
Add 1.2 litres of chicken stock (I made mine with Bouillon stock cubes).
Bring to the boil, add a tied sprig of parsley and let it simmer for 25 minutes.
When the time is up, remove the parsley bouquet and whizz everything with a handheld blender until it is all creamy.
Toast some rye bread and cut into small squares to form the croutons.
Grate some parmesan over the croutons and place under the grill for a few minutes until it starts to melt.
Place a few cheesy croutons on each bowl of soup and serve. Yummy!